640544684 has 24 divisors (see below), whose sum is σ = 1235258640. Its totient is φ = 288759744.

The previous prime is 640544669. The next prime is 640544731. The reversal of 640544684 is 486445046.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140999 + ... + 145470.

It is an arithmetic number, because the mean of its divisors is an integer number (51469110).

Almost surely, 2^640544684 is an apocalyptic number.

It is an amenable number.

640544684 is a deficient number, since it is larger than the sum of its proper divisors (594713956).

640544684 is a wasteful number, since it uses less digits than its factorization.

640544684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286529 (or 286527 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 41.

The square root of 640544684 is about 25308.9842546081. The cubic root of 640544684 is about 862.0182829620.

The spelling of 640544684 in words is "six hundred forty million, five hundred forty-four thousand, six hundred eighty-four".